1. Field of the Invention (Technical Field):
The present invention relates to retaining devices for heat sinks for electronic components.
2. Background Art:
Note that the following discussion refers to a number of publications by author(s) and year of publication, and that due to recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
It is well known in the art to use heat sinks for removing heat generated by electronic components in various types of electronic equipment, such as computers, televisions, stereo, etc. Heat sinks are typically formed so as to comprise a flat plate with a plurality of fins disposed at a right angle to the flat plate and preferably formed integral therewith, such as by extrusion or the like. In use, the flat plate of the heat sink is in direct contact with a component and for that reason may have the same size and shape as the body of the component. In order to effect good heat transfer from the surface of the electronic component to the base plate of the heat sink, it is desirable to bias the two surfaces into contact. Such contact should withstand the various forces to which the electronic equipment may be subject, such as shocks received in transport of the electronic equipment. Moreover, such electronic equipment may be in service for many years, and it is desirable that the biased contact be maintained over such extended period of time. Furthermore, since the heat sink and component may be subjected to various operating temperatures, it is desirable that the effective heat transfer contact be unaffected by such temperature changes.
In order to effect this contact, it may initially appear that using a standard fastener of some type may be suitable. However, there is an additional consideration in the retention of the heat sink to the component, which is the necessity for the retaining device to be inexpensive, and extremely easy to insert and de-insert. The latter is particularly a problem since it affects both assembly of the heat sink to the component during initial manufacture of the electronic equipment and throughout the life of the equipment it may be necessary to d-insert the retainer device so as to release the heat sink from the component, such as may be required where the component has failed and must be replaced.
Various types of heat sink retainer devices are disclosed in the prior art which attempt to meet these desiderata. For example, in U.S. Pat. No. 5,881,800, there is shown a heat sink device with retainer clips formed from plastic and having an "arrowhead locating bolt" that passes through an opening in the heat sink and a corresponding opening in a printed circuit board so as to clamp the two together. In U.S. Pat. No. 5,870,286, there is shown a heat sink and retaining clips comprising push pin assemblies and a separate compression spring that biases the heat sink and base plate of the heat sink and a printed circuit board into contact. Each of the push pin assemblies include flexible legs that support locking barbs. Similar devices are shown in U.S. Pat. Nos. 5,730,210 and 5,384,940.
While these retainer dips for heat sinks may be suitable for the particular applications as shown in the subject patents, it is desirable to have as much spring force to bias the heat sink and component together, and the present invention provides for a unique configuration that creates a sustained and substantial biasing pressure.